1. Field of the Invention
The present invention relates to a light receiving device for allocating and storing photoelectrons generated by photoelectric conversion.
2. Description of the Related Art
Known conventional applications of image sensors include technologies using a time-of-flight (TOF) method for measuring a distance to a target object in a contactless manner. In one known technology using the TOF method, photoelectrons (negative electric charge) generated in a photoelectric conversion element are allocated and then read out. In Ryohei Miyagawa and Takeo Kanade, “CCD-Based Range-Finding Sensor”, IEEE Transactions on Electron Devices, Vol. 44, No. 10, October 1997, pp. 1648-1652 and Ryohei Miyagawa and Takeo Kanade, ITE Technical, Vol. 19, No. 65, pp. 37-41 (November 1995), a pulsed light is emitted from a light-emitting device in an emission period and is not emitted therefrom in an emission stop period, the light-emitting device is driven to repeat the emission period and the emission stop period with the same time length at a duty ratio of 50%, the pulsed light is detected in synchronism with the periods, and thus generated photoelectrons are distributed in two directions. In addition, in Japanese Laid-Open Patent Publication No. 2010-032425, the photoelectrons generated in the photoelectric conversion element are distributed in four directions.